Electrical device



Jan. 12, 1960 Filed Dec. 27, 1957 D. E. CLARKE ELECTRICAL DEVICE 3 Sheets-Sheet 1 yLbMMIAQMmA- Jan. l2, 1960 D. CLARKE 2,921,165

ELECTRICAL DEVICE Filed Dec. 27, 1957 3 Sheets-Sheet 2 I I I 1|'. 'n f 32 a a I l l X "Il Z x x x: 44 L --.J 44

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Jan. 12, 1960 DIE. CLARKE ELECTRICAL DEVICE 3 Sheets-Sheet 3 Filed Dec. 27, 1957 n nr EC a w E United States Patent ELECTRICAL DEVICE ,David E. Clarke, Norton, Mass., assignor to Texas Instruments Incorporated, a corporation of Delaware Application December 27, 1957, Serial No. 705,610

7 Claims.V (Cl. 200-88) This invention relates to a winding for an electrical device and to a method of making the same.

An object of this invention is to provide a novel and improved winding for an electrical device, and to provide a novel and improved method of making said winding. A further object of this invention is to provide a new and improved electrical device 'incorporating such a winding, and to provide a novel strip member capable of forming such a winding.

Another object of this invention is to provide an improved winding having a substantially reduced stack height as compared with previously known windings having the same or a greater number of turns of an electrical conductor of the same or a greater cross-sectional area. A further object of this invention is to provide an improved method of making such a winding.

Another object of this invention is to provide an improved winding which is inexpensive, compact, eflicient, sturdy and dependable in operation.

Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, steps and sequence of steps, features of construction and manipulation, and arrangefments of parts, all of which willbe exemplified in the structures and methods hereinafter described, and the Vscope of the application of which will be indicated in the following claims.

In-the accompanying drawings, in which several of 4various possible embodiments of the invention are illustrated: v 1 i Fig. 1 is an elevational view of an electrical switch with the casing broken away, this according to one embodiment of the invention;

Fig. 1A is a fragmentary, sectional view on an enlarged scale and showing a portion of the structure shown in Fig. l when modied to include a return spring for the latch bar;

Fig. 2 is a sectional view taken along line 2-2 of .Fig. 1;

Fig. 3 is an enlarged, fragmentary, cross-sectional view taken along line 3-3 iu Fig. 2;

Fig. 4 is a perspective view of a strip member capable of being formed yinto the winding incorporated in the embodiment as shown inL Fig. l;

Fig. 5 is a perspective view of said strip member and two insulating members, this ligure illustrating the manner in which the parts shown may be partially formed and assembled prior to final folding of the strip member to the conformation shown in Fig. 1;

Fig. 6 is a slightly enlarged View corresponding to Fig. 4 but showing a strip member according to a second embodiment of the invention; l I

Fig. 7 is an enlarged, fragmentary, cross-sectional view corresponding to Fig. 3 but according to said second embodiment; and

Fig. 7A is a view similar to Fig. 1A but incorporatmg the winding oflsaid second embodiment.

Referring to Fig; 1, an electricaldevice according to n 2,921,165 Patented Jan. 12, 1960 ice,

a first embodiment of the invention is shown taking the form of a circuit breaker generally indicated by the numeral 10. `Circuit breaker 10 is shown with electrical, make and break contacts 12 and 14 in the contacts-open position and with push button 16 in the retracted position. Briefly, push button 16 is depressed downwardly as viewed in Fig. 1 to move a link 18 downwardly thereby to wedge members 20 and 22 apart about their mutual pivotal mounting pin 24. When push button 16 is in its fully depressed position, member 22 is pivoted in a clockwise direction about pivot point 24 to bring contact 12 into engagement with contact 14 and latch-engageable member 20 is pivoted in a counterclockwise direction to bring a projection 26 carried by the latter into engagement with a latch bar 28. Latch bar 28 is pivotally mounted at 30 for movement toward the left as viewed in Fig. l under the inuence of a composite, thermally responsive element 32 and against the bias of a compression spring (not shown in Fig. l). That is, upon heating of thermally responsive member 32 due to excessive electrical current flow therethrough, the distal end of member 32 is movable to the left as shown in Fig. l against the latch bar 28 or means carried thereby to move the latch bar to the left out from under projection 26 carried by latch-engageable member 20. The result is that contact carrier 22 is released, and under the influence o-f springs 34 and 36, the latter quickly moves to the contacts-open position as shown in Fig. l. For the specific features of construction and operation of this circuit breaker except, of course, for the details of construction yand operation of the instant invention vas particularly pointed out hereinafter, reference is made to the circuit -breaker shown and described in U.S. Patent No. 2,813,168, granted on November 12, 1957 to Mascioli et al. Fig. l of the drawing corresponds to Fig. 2 of this patent and shows one phase of a three phase circuit breaker. For the purposes of the invention, however, it will be clear that each of the outer phases could be eliminated since the invention applies as well to a single phase* device. Referring to Fig. lA, the single phase device as well as the center section or one of the central sections of a multi-phase circuit breaker according to this invention includes a compression spring 62 resiliently to bias the latch bar 28 to the right. The spring 62 is mounted on one of the pole pieces 54A, the latter being of reduced diameter and the insulating collar 168 surrounding a portion of spring 62, all as clearly explained in the above-mentioned patent.

With contacts 12 and 14 in closed position, an electrically conductive path is established through circuit breaker 10 leading from terminal 38 through contact 14, contact 12, contact mounting member 40, flexible lead 42, thermally responsive element 32, members 44, 44, applicants novel winding 46 for magnetizable core 48, and finally through terminal 50. In many cases latch bar 28 will have moved to releasing position under the iniluence of thermally responsive member 32 before the latter and other parts of the circuit breaker and circuit being protected have become deleteriously overheated. However, it is important that under short-circuit and otherhigh current overload conditions, latch bar 28 be moved to the left quickly to effect movement of contact 12 to the contacts-open position before thermallyresponsive member 32 and other parts of the circuit breaker 10 and circuit being protected become overheated. For eX- ample, overheating of thermally responsive member 32 could result in the latter being annealed thereby upsetting the calibration of the device Vand/or rendering the device inoperative. The function of quickly opening the contacts under high current overload conditions is provided by the electromagnet generally indicated by the numeral 52 and which includes winding 46 and U-shaped Asuccessively cut apart from one another.

core 48. It will be noted that this electromagnet also aids thermally responsive member 32 in effecting unlatching under comparatively lower current overload conditions.

Core 48includes two pole pieces 54 and 56'connected by a yoke 58, the core 4S beingformed of magnetizable material such as soft iron.y Upon theocc'urrenceof` a fault resulting in a short-circuit current' owing along the electrically conductive path` through circuit breaker as described above, electromagnet 52 strongly and quickly attracts armature 60 carriedv by latch bar 28" to the left as viewed in Fig. 1. Movement of latch bar28 to the left as viewed in Fig. lfis resisted by compression spring 62, the latter maintainingfthe latch bar in the to the shape shown in Fig. 4. ,It lwill be obvious that a v plurality of successively interconnected strips couldl be stamped from a continuous length of stock and the strips step, strip 46 is provided withav terminal portion 6 4'at one end and a terminal portion 66 at the other end.A In- By the cutting termediate terminal portions 64 and 66, strip member 46 is provided by the cutting step with a plurality of successive slots 68, 70, 72, 74, 76 and 78. Each of the slots in succession along4 the length of the strip,l alternately from opposite lateral edges ofthe strip inwardly thereof.` 1 5 Each of slots 68, 70, 72, 74, 76 and 78 includes an aperture numbered respectively in Fig. 4 as 80, 82, 84,86, 88 and 90. It will be apparent from Fig. 4 that each of apertures 80, 82, 84, 86, 88 and 90 is` aligned with eaich of the others. However, for the embodiment as shown in Fig. l, as will become apparent later in this description, it is only necessary that apertures 80, 86 and88 be aligned with each other and that apertures 82-84 and 90 be aligned with each other. n l

Continuing vwith the method-of making the Winding 46 as shown in Figs. l and 3, the blanked-out strip as shown in Fig. 4 is folded or bent along a transverse line between each succeeding pairof mutually adjacent slots. Referring to Fig. 4 the transverse fold line between pair of slots 68 and 70 and pair of slots 72 and 74 is indicated by the reference-numeral 92 and the transverse fold -line between pair of slots 72 and 74 and pair of slots 76 and 78 is indicated by the numeral 94. Referring to the drawing, -fold lines 92 and 94 divide member 46 into three sections, each of the sections providing a pair of kmeans of insulators 96 and 98Which are formed, for

example, of mica. Insulator 96 is provided with a pair `of apertures 100 and 102, and insulator 98 is provided with aperturesp104 and `106. A tapered pin `is inserted in each of the apertures in one of the end sections of the strip and the stripis then further bentalong each of fold lines 92and94 Vto the substantiallyfiiat*conformation shown in Leach of Figs. 1 and 3. It will be apparent that the tapered pins aid in aligning each of apertures 90, 100,

84, 104 and 82, and in aligning apertures 88, 102, 86, 106

and as the strip is bent to substantially at condition. In assembling the winding 46 with core 48 of the electromagnet 52, an insulating collar 108 is telescoped onto each of pole pieces 54 and S6 and the winding is then assembled with the electromagnet, all |as shown in Figs. 1, 2 and 3. Terminal portion 64 of the strip member is electrically connected to members 44, 44 by means of welds at 110, 110, and terminal portion 66 of the strip member is electrically connected to terminal 50 as by means of a weld 114. The preferred sequence is to weld the terminal portions of strip member 46 to terminal 50 and to members 44, 44 and assemble core 48 of the electromagnet with the winding; and then to mount the subassembly comprising members 44, 44, winding 46 with insulating means 96, 98, and terminal 50 in the casing 116, after which this subassembly is secured in place by means of screws 112 and 11S.

When contacts 12 and 14 of circuit breaker 10 rare in closed position, the current ow through winding 46 leads from end portion 66 (see Figs. 3 and 5) with a half turn about pole piece 56 and then, in succession, with a full turn about pole piece 54, a full turn about pole piece 56, and a half turn about pole piece S4 to terminal portion 64. As viewed in Fig. 2, eachtum and half turn of winding 46 about pole piece 56 is in the counterclockwise direction and each turn and half turn about pole piece 54 is in the clockwise direction. Accordingly, .each of the turns and half turns adds to or aids each of the others inproducing the total eld strength of the electromagnet.

It will be clear then that each section of strip member 4` 46 (as rdefined by fold lines'92A and 94) provides a` full turn of the winding about the core 48 ofthe electromagnet 52. Strip 46, providing three sections, provides three full turns about the core of electromagnet 52. It is apparent, of course, that the winding of this invention is 4notlimited toy three turns only. Among the advantages of the improved winding of this invention, the stack height of the winding is reduced, the cross-sectional area of the winding is increased, and a compact, sturdy and eicient winding is provided.

Referring to Figs.; 6 4and 7, a second embodiment of the invention is shown. Parts of the embodiment shown in Figs. 6, 7 and 7A are or may be substantially identical with those of the embodiment as shown in Figs. 1-5 except as ,pointed out hereinafter. In this regard, those parts of the embodiment shown in Figs. 6 and 7 which have primed reference numerals are or may be identical with their respective counterparts in Figs. 1-5, these respective counterparts having the same but unprimed reference numerals.

Referring to Fig. 6, a strip member is shown which has applied thereto a coating 122 of a suitable electrically insulating, heat resistant material such as Teflon; the latter being a registered trademark of E. I. du Pont de Nemours & Co., Wilmington, Delaware. Strip member 120 as shown in Fig. 6, with the exception of the added insulation coating 122, is or may be identical with the strip member 46 of the rst embodiment described above and as shown in Fig. r4, `and is formed in the same manner'. It is noted that the coating 122 of insulation terminates short of theterminal ends 124 and V126 of strip member 120. After'forming strip member 120 as described with respect to the making of the strip member as shown in Fig. 4, the insulation coating 122 is applied by dipping or spraying. Terminal portions 124 and -126 may be masked prior to dipping or spraying strip member 120 with the vinsulating material, or alternatively, strip member 120 may be entirely coated with the insulating-material and subsequently the coating covering terminal portions 124 and 126 may be removed in appropriate manner such as by scraping. Strip member 120 is then partially Vbent along fold lines 128 and 130 in the same manner as thestrip member 46 is partially bent to bring the latter to the conformation shown in Fig. 5. Subsequently, a tapered pin is inserted in each of the apertures of the slots of one of the end sections of strip 120 and the strip memberfis folded at to the conformation shown in Fig. 7. As with the previously described embodiment, the bends made in the terminal portions 124 and 126 can be efected prior to, subsequent to or 'at the time of final bending of the strip to bring it to the conformation shown in Fig. 7. Of course, with the embodiment of Figs. 6 and 7 whereby strip member 120 is provided with the coating 122 of insulation, insulators such as insulators 96 and 98 as described with respect to the Figs. l-5 embodiment are eliminated since coating 122 effectively insulates the exposed surfaces of each of the sections of strip 120 from each of the others. The winding formed by strip member 120 is assembled with the remaining parts of the device in the same manner as that described with respect to the embodiment of Figs. 1 5. Fig. 7A corresponds to Fig. lA of the first embodiment described herein and shows the manner in which spring 62' is mounted on pole piece 54A. It will be apparent that insulating collars or sleeves 108 and 108 as shown in Figs. lA and 7A, respectively, provide the function of retaining the return Aspring on 'the `adjacent pole piece as well as acting as an (electrical insulator between the winding and that pole piece.

It will be noted that a portion of the aperture of each mf the slots in the winding according to both of the lembodiments described herein lies at a lesser distance from the respective next adjacent fold line than the junction of -that aperture with the remainder of the respective slot. Also, the remainder of each of the slots :is substantially parallel with the fold line next adjacent thereo. Among the advantages of this feature, the wind- ;ing or strip is thereby rigidiiied, an additional portion is ,provided to be grasped -by the means used in bending the :strip along the fold lines, and folding of the strip is facilitated.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results obtained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense.

Dimensions of certain of the parts as shown in the drawing have been modified for the purposes of clarity of illustration.

I claim:

1. A strip of electrically conductive material for use as the winding of an electrical device, said strip providing a plurality of slots extending transversely and inwardly of the strip from the lateral edge of the latter opposite to that from which each of the next adjacent slots extends, said strip being folded substantially flat along a transverse line between each pair of succeeding slots to form a plurality of successive sections defined by the fold lines and lying in side-by-side relationship with each of said sections including a pair of slots each opening on opposite lateral edges of said strip and each pair of slots of each section being aligned respectively with -a corresponding pair of slots in an adjacent section, each of said slots including an aperture aligned with the aperture of the next adjacent slot of the next adjacent section; the juncture of the aperture of each of said slots with the remainder of that slot lying at a greater distance from the next adjacent fold line than the edge of said aperture nearest that fold line, and said remainder of each of said .slots extending substantially parallel with the fold line next adjacent thereto.

2. An electromagnet comprising a U-'shped core and a winding, said winding including a at strip formed of electrically conductive material land providing a plurality of slots extending transversely and inwardly of the strip from the lateral edge of the latter opposite to that from which each of the next adjacent slots extends, said strip being folded substantially flat along a transverse line between each pair of succeeding slots to form a plurality of successive sections defined by the fold lines and lying in mutually adjacent, side-by-side relationship with each of said sections including a pair of slots each opening on opposite lateral edges of said strip and each pair of slots of each section being aligned respectively with a corresponding pair of slots in an adjacent section, said U- shaped core being formed of magnetizable material and providing two pole pieces, each of said pole pieces lying within a portion of'one of the slots of each of said scctions, and means electrically insulating each of said sections from those mutually adjacent thereto.

3. An electrical switch including a pair of make and break, electrical contacts; a latch mechanism for retaining said contacts in closed position; said mechanism including a member movable for effecting release of said latch mechanism and opening of said contacts; an armature carried by said member; an electromagnet for attracting said armature and so moving said member; said electromagnet comprising a core formed of magnetizable material and having two pole pieces and a winding for said pole pieces; said winding including a flat strip formed of electrically conductive material and providing a plurality of slots extending transversely and inwardly of the strip from the lateral edge of the latter opposite to that from which each of the next adjacent slots extends; said strip being folded substantially flat along a transverse line between each pair of succeeding slots to form a plurality of successive sections defined by the fold lines and lying in side-by-side relationship with each of said sections including a pair of slots each opening on opposite lateral edges of said strip and each pair of slots of each section being aligned respectively with a corresponding pair of slots in an adjacent section, each of said slots including an aperture aligned with the aperture of the next adjacent slot of the next adjacent section; the juncture of the aperture of each of said slots with the remainder of that slot lying at a greater distance from the next adjacent fold line than the edge of said aperture nearest that fold line, and said remainder of each of Said slots extending substantially parallel with the fold line next adjacent thereto, each of said pole pieces lying respectively within an aperture in each of said sections of said winding whereby said winding leads electrically with a number of turns about said core in a substantially gure 8 path; and means electrically insulating from each other the mutually adjacent portions of said strip on opposite sides of each of said transverse lines.

4. The winding as set forth in claim l and wherein each of said apertures is circular and tangent to the side of its respective slot which is furthest from its adjacent fold line and intersects the other side of the slot closest to its adjacent fold line.

5. The article as set forth in claim l including a fiat layer of electrically insulating material disposed between each pair of succeeding, side-by-side sections, each of said layers of insulating material providing an aperture in alignment with a portion of one of the slots of each of said sections.

6. The article as set forth in claim l wherein the outer surfaces of said sections of the strip are coated with a layer of electrically insulating material.

7. The article as set forth in claim 1 wherein said strip carries at each end a terminal portion adapted for electrical connection of said strip in an electrical circuit.

(References on following page) 7 References Citedin, thele, of this patent UNITED STATES PATENTS n Polydoroi* Nov. 13 19,28 2,014,524 Franz Sep't; 17, 1935 2378133168` Mascioli' Nov. 12; 1 957 8 FOREIGN PATENTS Great Britain Dep. 19, 19,13 Germany Oct. V14, 1931 Austria v-- Oct., 245, 1937/1 Germany ,..-k Oct. 31:,V 1938. 

